In Oregon, The GMO Wheat Mystery Deepens : The SaltGovernment investigators are trying to solve an agricultural whodunit: How did genetically engineered wheat that was never approved for sale end up in a farmer's field in Oregon? Some are raising the possibility of sabotage; others suspect simple human error.

There is a mystery that's turning out to be hard to solve in the wheat fields of Oregon as baffling as any fictional who-done-it. You may have heard of it - genetically engineered wheat suddenly turned up in a farmer's field a few months ago, seemingly out of nowhere. This kind of wheat isn't supposed to be growing anywhere. The company Monsanto tested it a decade ago, but never asked for permission to sell it.

Government investigators have been trying to figure out where this rogue wheat came from. NPR's Dan Charles has more.

DAN CHARLES, BYLINE: The plants were revealed when the farmer sprayed one of his fields with the weed killer glyphosate, also known by its trade name Roundup. Everything died except for some clumps of wheat apparently sprouting from grain that was leftover in the field from last year's crop.

It was so strange, the farmer wondered if this wheat might be genetically modified to be resistant to glyphosate. He knew that the company Monsanto had once created such wheat. He called a scientist at Oregon State University, Carol Mallory-Smith.

CAROL MALLORY-SMITH: I said, well, I didn't think so.

CHARLES: Mallory-Smith told the farmer it didn't make sense. Monsanto's last field trials of glyphosate-resistant wheat in Oregon were 12 years ago.

MALLORY-SMITH: So I was pretty skeptical, but I said, if you send me some samples, I'll test it.

CHARLES: To her amazement, the tests came back positive. Seven weeks ago, the U.S. Department of Agriculture confirmed that this was indeed genetically-engineered wheat. It launched an investigation. The USDA has two big questions about this wheat. First, has it been growing anywhere else?

Hundreds of millions of dollars could hang on the answer. If unauthorized genes are in America's wheat harvest, some customers, especially big ones in Japan and Korea say they won't buy it. Fortunately for America's wheat farmers, no one so far is finding anymore so-called GMO wheat. GMO for genetically modified organism.

The USDA has tested thousands of samples collected from farms and seed companies. No one has reported finding any GMOs, anywhere. Blake Rowe who is CEO of the Oregon Wheat Commission, says he thinks Japan, which has suspended its purchases of U.S. wheat, will start buying again when it's sure the wheat is GMO-free.

BLAKE ROWE: I think we're confident they will come back to the market, but there's a lot of concern about how quickly that will happen.

CHARLES: Meanwhile, though, every test that comes back negative is making it harder to answer the second big question. How in the world did wheat containing Monsanto's new gene, what the company calls the CP4 gene, ever get into the Oregon field? Because there's no trail leading from that farm back to Monsanto's research operation. And Monsanto says it's sure no wheat escaped from is field trials.

Across the wheat-growing areas of the Pacific Northwest, farmers and wheat dealers now are trading theories. The wildest scenario came from the chief technology officer of Monsanto, Robert Fraley, in a conference call with reporters.

ROBERT FRALEY: The fact pattern indicates the strong possibility that someone intentionally introduced wheat seed containing the CP4 event in his field, sometime after the farmer initially planted it.

CHARLES: And why would someone do this?

FRALEY: It's fair to say that there are folks who don't like biotechnology and would use this as an opportunity to create problems.

CHARLES: Fraley speculates that troublemakers could have stolen wheat from one of Monsanto's field trials, kept it for a decade, then planted it and waited for the farmer to discover it.

BOB ZEMETRA: That is a stretch.

CHARLES: Bob Zemetra one of the wheat breeders at Oregon State University says that scenario seems like an awfully roundabout and passive way to attack Monsanto. Zemetra thinks an ordinary mistake is more likely. Let's say someone involved in Monsanto's GMO wheat trials ten years ago just puts a bag of wheat in the wrong place.

ZEMETRA: Or you have a bag that gets mislabeled and gets put on the shelf and just sits there.

CHARLES: The way Zemetra imagines it, somebody picks up that bag, maybe years later, and thinks it's normal, conventional seed. Zemetra admits his scenario isn't exactly convincing, either. You'd think if GMOs had gotten into the seed supply, the USDA's tests would have found them more widely. The head of the USDA's investigation, Bernadette Juarez, says the agency is now analyzing the genetic makeup of the GMO wheat from that one field, to figure out exactly which genetic variety of wheat it is.

That should show which of Monsanto's many different field trials of different varieties this GMO wheat came from. Maybe then they'll be able to pick up a trail of rogue wheat and figure out how it got to a farm in Oregon. Or maybe, it will remain a mystery. Dan Charles, NPR News.

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